This invention relates to the collection of sunlight and specifically to improvements in a solar thermal concentrating collector.
By the 1970s, interest in solar energy collection had grown substantially. It was around that time that investigators developed a better understanding of stationary solar concentrators. This type of concentrator was attractive since it could potentially collect and focus light onto a pipe without following the sun.
One stationary solar concentrator had the general appearance of a “wedge” and early versions of the collector are represented in U.S. Pat. Nos. 4,074,704, 4,282,862 and 4,344,417. In each patent the inventor recognized that the focal temperature could be doubled if rays were initially directed into the wedge toward the focus. In order to achieve this, each inventor placed an array of prisms on top of the wedge. Prisms did have the unique ability to collect light with a wide acceptance angle, but there was a problem: the prisms could only direct rays weakly, by refraction. Without a complete solution for collecting and directing light, the wedge remained a low temperature solar concentrator.
In publication number US 2010/0165495, an optic is shown that is specifically designed to direct light into the wedge.